EP0480768A2 - Corps fritté en céramique, procédé de fabrication et isolateur des bougies en cette matière - Google Patents

Corps fritté en céramique, procédé de fabrication et isolateur des bougies en cette matière Download PDF

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Publication number
EP0480768A2
EP0480768A2 EP91309412A EP91309412A EP0480768A2 EP 0480768 A2 EP0480768 A2 EP 0480768A2 EP 91309412 A EP91309412 A EP 91309412A EP 91309412 A EP91309412 A EP 91309412A EP 0480768 A2 EP0480768 A2 EP 0480768A2
Authority
EP
European Patent Office
Prior art keywords
magnesia
nitride
ceramic body
mixture
ppm
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP91309412A
Other languages
German (de)
English (en)
Other versions
EP0480768A3 (en
EP0480768B1 (fr
Inventor
Makoto C/O Ngk Spark Plug Co. Ltd. Sugimoto
Mamoru C/O Ngk Spark Plug Co. Ltd. Musasa
Hiroyuki C/O Ngk Spark Plug Co. Ltd. Tanabe
Masahiro C/O Ngk Spark Plug Co. Ltd. Konishi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Niterra Co Ltd
Original Assignee
NGK Spark Plug Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NGK Spark Plug Co Ltd filed Critical NGK Spark Plug Co Ltd
Publication of EP0480768A2 publication Critical patent/EP0480768A2/fr
Publication of EP0480768A3 publication Critical patent/EP0480768A3/en
Application granted granted Critical
Publication of EP0480768B1 publication Critical patent/EP0480768B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
    • C04B35/581—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on aluminium nitride
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/38—Selection of materials for insulation

Definitions

  • This invention relates to a sintered ceramic body for a spark plug insulator which needs good insulation properties at high ambient temperature and good thermal conductivity.
  • a nitride-based sintered ceramic body has been employed since the sintered ceramic body has good thermal conductivity.
  • the nitride-based sintered ceramic body tends to lose its electrical insulation when exposed to high temperatures and grows crystals treeing over the surface of the sintered ceramic body when high voltages are applied.
  • a sintered ceramic body comprising magnesia uniformly diffused into grains of a nitride-based ceramic, the amount of diffused magnesia being between 20 ppm and 100 ppm inclusive, calculated by reducing the magnesia to elemental magnesium.
  • diffusion of magnesium is measured by the EPMA method.
  • the quantity, or concentration of magnesium may be measured by fluorescent analysis.
  • the nitride-based ceramic body may include auxiliary agents up to 10% by weight selected from the group consisting of alkali-based earth metals, rare-earth elements and mixture of the alkali-based earth metals and the rare-earth elements, the weight percentage of the auxiliary agents being calculated by reducing the agents to their elemental forms.
  • the nitride-based ceramic body is suitable for use in the insulator of a spark plug.
  • magnesia MgO
  • Mg++ magnesium ions
  • a magnesium (Mg) concentration of less than 20 ppm has significantly no affect on-the elevated insulation property.
  • a concentration exceeding 100 ppm deteriorates the thermal conductivity.
  • auxiliary agents up to 10% by weight can lead to improved properties in the sintered ceramic body.
  • Addition of the auxiliary agents exceeding 10% by weight can lead to improved properties in the sintered ceramic body.
  • Addition of the auxiliary agents exceeding 10% by weight reduces the thermal conductivity intrinsically provided with the nitride-based ceramic body.
  • the resulting spark plug is capable of maintaining good insulation properties and good thermal conductivity at a wide range of operating temperatures.
  • Aluminum nitride (ARN) powder is prepared whose granular size measures 1.5 ⁇ m in average diameter (sedimentation analysis) with an oxygen-laden rate of 0.8% by weight.
  • Auxiliary agents employed herein are all 99.9% purity selected alone or combination from the group consisting of yttrium oxide (Y203), calcium oxide (CaO), strontium oxide (SrO), scandium oxide (SC2O3), neodymium oxide (Nd2O3) and europium oxide (Eu2O3).
  • the device shown in Fig. 1 is used to measure insulation resistance of counterpart test pieces and test pieces according to the invention at a temperature of 700°C.
  • the device has brass-made electrodes 100, 200, a heater 300 and a 500-volt digital resistance meter 400.
  • laser flash method is used.
  • An amount of magnesium (Mg) produced by reducing its oxide (MgO) is measured by means of I.C.P. (Isostatic Cold Press).
  • Amounts of the auxiliary agents and aluminum are each measured on the basis of fluorescent-sensitive X-ray detection.
  • test pieces Nos. 1 ⁇ 11 according to the invention are manufactured as follows:
  • the compact plate is milled to be 50 mm in diameter and 1.0 mm in thickness when it is employed in the measurement of its electrical resistance, while being milled to be 10 mm in diameter and 2.0 mm in thickness when it is employed in the measurement of its thermal conductivity.
  • the magnesium diffusion processes are as follows:
  • test piece Nos. 1 ⁇ 11 of the invention it is found that all of them have good insulation resistance and favorable thermal conductivity under the temperature of 700 °C, thus making the sintered body well-suited for a spark plug insulator.
  • a spark plug insulator needs the thermal conductivity of more than 90 W/m and the insulation resistance of more than 50 M ⁇ at 700 °C from treeing-preventing viewpoint.
  • Aluminum of less than 3 wt % increases the thermal conductivity with the sintered ceramic body structurally fine-grained.
  • a spark plug insulator was made in accordance with the test piece Nos. 1 ⁇ 11. After a center electrode, a resistor and a terminal electrode were placed within an axial bore of the insulator through a conductive glass sealant, and the insulator placed within a metallic shell to form a spark plug capable of preventing misignition at a wide range of operation temperatures.
  • nitride-based ceramic categorically includes sialon (Trademark) and aluminum nitride oxide (AlON) as nitride oxide-based ceramic.
  • barium (Ba) is an appropriate selection as alkali-based earth metal, while lanthanum (La), cerium (Ce) and dysprosium (Dy) are appropriate selections as rare-earth elements.
  • the primarily sintered compact plate is secondarily sintered within a boron nitride shell (BN shell) whose inner wall is coated with magnesia (MgO) as indicated by BN + MgO shell.
  • the secondary sintering temperature preferably ranges from 1600 °C to 1900 °C.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Ceramic Products (AREA)
  • Spark Plugs (AREA)
EP91309412A 1990-10-12 1991-10-14 Corps fritté en céramique, procédé de fabrication et isolateur des bougies en cette matière Expired - Lifetime EP0480768B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP02274896A JP3135558B2 (ja) 1990-10-12 1990-10-12 スパークプラグ
JP274896/90 1990-10-12

Publications (3)

Publication Number Publication Date
EP0480768A2 true EP0480768A2 (fr) 1992-04-15
EP0480768A3 EP0480768A3 (en) 1992-10-07
EP0480768B1 EP0480768B1 (fr) 1995-05-24

Family

ID=17548039

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91309412A Expired - Lifetime EP0480768B1 (fr) 1990-10-12 1991-10-14 Corps fritté en céramique, procédé de fabrication et isolateur des bougies en cette matière

Country Status (6)

Country Link
US (1) US5198394A (fr)
EP (1) EP0480768B1 (fr)
JP (1) JP3135558B2 (fr)
BR (1) BR9104437A (fr)
CA (1) CA2053360C (fr)
DE (1) DE69109995T2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0548424A1 (fr) * 1990-09-07 1993-06-30 Ngk Spark Plug Co., Ltd Corps fritté en céramique et procédé de fabrication d'un isolateur de bougies à partir de celui-ci

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5760532A (en) * 1991-12-26 1998-06-02 Ngk Spark Plug Co., Ltd. Sintered ceramic body for a spark plug
JP4369963B2 (ja) * 2007-06-22 2009-11-25 日本特殊陶業株式会社 スパークプラグ用絶縁体の検査方法
US8013617B2 (en) * 2008-03-10 2011-09-06 Ngk Spark Plug Co., Ltd. Test method and apparatus for spark plug ceramic insulator

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5765683A (en) * 1980-10-10 1982-04-21 Nippon Soken Ignition plug

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, vol. 82, no. 22, 1974, Columbus, Ohio, US; abstract no. 144186F, A. EBISAWA ET AL.: 'Nonporous silicon nitride porcelain' *
JOURNAL OF MATERIALS SCIENCE vol. 22, no. 11, November 1987, LONDON,GB pages 4056 - 4060; M. ZULFEQUAR ET AL.: 'Electrical conductivity of hot-pressed AlN ceramic' *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0548424A1 (fr) * 1990-09-07 1993-06-30 Ngk Spark Plug Co., Ltd Corps fritté en céramique et procédé de fabrication d'un isolateur de bougies à partir de celui-ci

Also Published As

Publication number Publication date
US5198394A (en) 1993-03-30
DE69109995D1 (de) 1995-06-29
EP0480768A3 (en) 1992-10-07
BR9104437A (pt) 1992-06-09
JP3135558B2 (ja) 2001-02-19
DE69109995T2 (de) 1995-09-21
EP0480768B1 (fr) 1995-05-24
CA2053360C (fr) 1996-08-06
JPH04149070A (ja) 1992-05-22
CA2053360A1 (fr) 1992-04-13

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